Pulp dewatering process
AssigneeAllied Colloids Limited
InventorRobert Reed
Life of this patent
Estimating the term…
Abstract
Dry market pulp is made by shearing a cellulosic suspension and draining it through a screen to form a pulp sheet which is then dried, and the productivity of the process is increased by adding a water soluble cationic polymer before the shearing and bentonite or other suitable inorganic material after the shearing.
Claims12
In a pulp making process for making dry market pulp that can subsequently be reslurried in water to form a paper-making suspension, wherein fibrous cellulosic material is pulped to form an aqueous suspension of cellulosic material, the suspension is subjected to one or more shear stages, the sheared suspension is drained through a screen to form a pulp sheet and the pulp sheet is dried to form the dry market pulp, the improvement comprising adding a water soluble polymer to the suspension before the shear stage or before one of the shear stages and adding an inorganic material to the suspension after such shear stage, said water soluble polymer promoting drainage of the suspension through the screen and being selected from the group consisting of cationic starch and substantially linear cationic polymers, and said inorganic material being selected from the group consisting of colloidal silica and bentonite, and wherein said water soluble polymer is added in an amount of 0.01 to 0.5% and said inorganic material is added in an amount of from 0.03 to 0.5% based on the dry weight of the suspension.
A pulp-making process in which fibrous cellulosic material is pulped to form an aqueous suspension of cellulosic material, the suspension is subjected to one or more shear stages, selected from cleaning, mixing and pumping stages comprising a centriscreen, a vortex cleaner, a fan pump or a mixing pump and the sheared suspension is fed to the head box of a lap pulp machine having a drainage screen, and the suspension is drained through the screen to form a pulp sheet and the sheet is dried to form dry market pulp, and in which 0.01 to 0.5% (dry weight) of a water soluble cationic polymer is added to the suspension before the final shear stage, said polymer being selected from polyethylene imine, polyamine epichlorhydrin products, polyamines, polydicyandiamide formaldehyde polymers, polymers of diallyl dimethyl ammonium chloride and polymers of acrylic monomers comprising a cationic acrylic monomer, and 0.03 to 0.5% (dry weight) of bentonite is added to the suspension substantially at the said head box.
Dependencies are inferred from the claim text.